Sexually transmitted infections have become a major public health problem in the global scenario. Use of contraceptives such as condoms can prevent exchange of body fluids thereby preventing transmission of certain sexually transmitted infections, however many other sexually transmitted infections gets transmitted through direct body contact. Pediculosis pubis is an uncommon sexually transmitted infection caused by the obligate ectoparasite Phthirus pubisor Crab lice. This case report of a 21 years old male patient who presented with submandibular lymphadenopathy and multiple erythematous macules on his face, chest and pubic region. He gave a history of multiple sexual exposures. Further examination and investigations revealed it to be a case of Pediculosis pubis. This parasite was collected, examined macroscopically, microscopically, and morphologically identified as Phthirus pubis.
Keywords: Erythematous macules, pediculosis pubis, submandibular lymphadenopathy
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Prasanth K, Ramachandran K, Dhanavelu P, Arumugam G. A rare case of submandibular lymphadenopathy due to pediculosis pubis infestation of facial hair: A case report. Ann Trop Med Public Health 2015;8:128-31
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Prasanth K, Ramachandran K, Dhanavelu P, Arumugam G. A rare case of submandibular lymphadenopathy due to pediculosis pubis infestation of facial hair: A case report. Ann Trop Med Public Health [serial online] 2015 [cited 2021 Apr 14];8:128-31. Available from: https://www.atmph.org/text.asp?2015/8/4/128/162381
Pediculosis is an infestation of lice on the human body. It can occur on any part of the body. The most common types are pediculosis capitis, pediculosis corporis, and pediculosis pubis.  Pediculosis pubis is caused by an infestation of the lice Pthirus pubis. Cases of pediculosis pubis have been associated with sexual intercourse with the infected partner(s) or by contact with shared towels, bed spreads, or clothing.  Pthirus pubis is primarily found in the pubic hair but on rare occasions can spread to the axilla, beard, eyebrows, eyelashes, or body hair.  There is a dearth of knowledge regarding the diagnosis of pediculosis pubis infection and most often, it is misdiagnosed.  This is a case report of lymphadenopathy of the submandibular lymph nodes secondary to pediculosis pubis infection of facial hair.
A 21-year-old unmarried male patient presented to the dental clinic with chief complaints of pain and swelling in the neck near the angle of the jaw on the left side since 15 days. He also complained of occasional fever and itching on his face, chest, and pubic region since the last 5 months. He also gave a history of unprotected sex with multiple homosexual partners.
On general examination, the patient was conscious and well-built, with normal gait and posture. He was mildly febrile (99.6° F). Extraoral examination revealed lymphadenopathy in the left submandibular region. His lymph nodes were firm and tender on palpation [Figure 1], [Figure 2], [Figure 3], [Figure 4] and [Figure 5]. Examination of his face, axilla, and pubic region demonstrated multiple pruritic erythematous macules. Careful examination through a magnifying lens showed multiple yellowish brown colored insects of size 1-1.2 mm. The insects were motile and multiple nits were visible in the chest and pubic region. Intraoral examination revealed dental caries in relation to tooth numbers 16, 17, and 47. Stains and calculus were present. All other findings were normal and noncontributory.
|Figure 1: (a) Microscopic view of Pthirus pubis (b) Microscopic view of nit (c) Nit of Pthirus pubis attached to the base of the hair shaft
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|Figure 2: (a) Pediculosis infestation of facial hair (b) Submandibular lymphadenitis of the left side of the face secondary to pediculosis
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|Figure 3: Pthirus pubis on the inner aspect of the thigh
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|Figure 4: Pthirus pubis in pubic hair
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|Figure 5: Pthirus pubis in the chest
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The insects were collected with tweezers for parasitological investigations. Macroscopic and microscopic examination confirmed the insects to be Pthirus pubis. The patient was also advised blood investigations, including complete blood count (CBC), enzyme-linked immunosorbent assay (ELIZA), and Venereal Disease Research Laboratory (VDRL), to rule out other sexually transmitted infections (STIs) like human immunodeficiency virus (HIV) and syphilis. CBC indicated anemia (10.1%), neutrophilia (79%), lymphocytosis (53%), and eosinophilia (9%). All other findings were normal and noncontributory.
The patient was advised to abstain from unsafe sexual practice with multiple partners and was educated about the parasite and its treatment. Ivermectin tablet of dosage 12 mg was prescribed orally as a single dose and was to be repeated the next week. Permethrin 1% solution was advised for topical use.  Antibiotics amoxicillin of dosage 500 mg and potassium clavulanate 125 mg three times a day (tid), and analgesics aceclofenac 100 mg and paracetamol 500 mg combination twice a day (bd) for 7 days was prescribed for lymphadenopathy. The patient was also told to disinfect his bed and clothing.
He was advised to follow up after a week, which revealed completely cured lymphadenopathy and erythematous macules. Two-weeks follow-up showed complete treatment from itching and lice.
Pthirus pubis infestation in humans is called pediculosis pubis. Pthirus pubis is an ectoparasite of the Anoplura group and Pediculidae family. This infection can occur at any age; however, it is more common in the sexually active age group (18-35 years).  Gavin hart et al. suggested that pediculosis pubis in men is associated with homosexuality and sexual exposure with multiple partners. , In this present case, the patient’s history of multiple homosexual exposures is a risk factor for pediculosis pubis.
Pthirus pubis occurs in regions rich in apocrine glands; hence, the pubic region, axillae, eyebrows, eyelashes, moustache, beard, and perianal region are commonly involved.  It can spread during vaginal, anal, or oral sex. In our case, multiple insects were found in the beard, chest, axilla, and pubic region. Multiple nits were also visible in the pubic region. Pthirus pubis feeds on human blood from cutaneous capillaries and reproduces by laying nits, which are adherent to the base of the hair shaft.  An adult female insect lays about three to four nits everyday, which hatch in 1 week.  After undergoing several developmental stages, the adult insect is formed in about 2 weeks.  The entire life cycle of the insect is around 30 days.  The injected saliva of the insect causes hypersensitivity reactions in the form of wheals or papules. The major symptom of pediculosis is pruritus. , Excoriations associated with pruritus may lead to secondary infections like pyoderma, which may lead to fever and regional lymphadenitis in severe cases.  In the present case, multiple erythematous macules were found all over the body and the patient had submandibular lymphadenopathy on the left side. Involvement of submandibular lymph nodes secondary to pediculosis pubis, in previous reports, is rare. Moreover, the noncontributory dental findings support the diagnosis of submandibular lymphadenopathy secondary to pediculosis pubis.
Pthirus pubis can be seen both macroscopically and microscopically.  The insect appears flattened with three pairs of legs, of which the last two pairs are adapted with specialized claws that help them adhere to the hair shaft. The insect measures 0.8-1.2 mm in length and appears yellow to light brown, which makes it difficult to spot.  The diagnosis is usually done by physical examination, which reveals multiple live insects or nits adhering to the base of the hair shaft. , Dermatoscopy may be useful in many cases.  Pediculosis is primarily sexually transmitted and often occurs in sex involving multiple partners; hence, screening for other STIs is mandatory. ,
According to Hermann Feldmeier and Jorg Heukelbach (2008), epidermal parasitic skin infections are neglected by health care providers and efforts to control these infections at the community level have rarely been undertaken.
Pediculosis is the most contagious STI, with an individual having 95% chance of acquiring the infection after one sexual exposure.  There is a dearth of literature regarding the epidemiology of pediculosis pubis infection,  particularly in India. Although morbidity associated with pediculosis is high, assessment regarding the burden of the disease does not exist. This is the first case report of submandibular lymphadenopathy associated with pediculosis pubis.
In conclusion, this case highlights the importance of parasitological investigation as a part of taking regular history and case diagnosis in dental as well as medical setups. It also emphasizes the importance of health education for the public, especially young adults, as these ectoparasitic infections are sexually transmitted and the patients affected are at a risk for other STIs. Cases like that of this patient may be atypical and often misguiding. This requires a multidisciplinary approach by the dermatologist and the dentist for prompt diagnosis and management.
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Department of Epidemiology, The Tamil Nadu Dr. MGR Medical University, No. 69, Anna Salai, Guindy, Chennai – 600 032, Tamil Nadu
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]